Can someone help me with this please?

I have a series of imported video clips. When they load the loading bar isn't displayed even though after a pause the videos will play so I assume that the code is working in order for the movie to go to the right frame to start playing the video clip. Can anyone explain to me why this is happening? and go to the 3D section and you'll see that the video's take a while to load but the loader doesn't appear.

Thanks in advance